Stepper motor driver alarms occasionally

The stepper motor driver sometimes alarms, turn the CNC machine power off then restart, the problem solved, then come again.

The alarms only appear after about half an hour machining.

Check below:

1-Is the mechanical parts of the machine in good condition or not?

2-Any poor contact from CNC controller to the stepper driver?

3-Is there any problem of the stepper driver?

4-The stepper motor is fine or not?

Checked step by step we found the stepper motor is not easy to rotate, check the 3 phase resistance and stepper motor insulting property with universal meter, there was indirect short circuit of the stepper motor winding, change the stepper motor and the cnc machine back to normal.